Aridicin aglycon: characterization of the amino acid components

Asymmetric Synthesis of Actinoidic Acid Derivatives

“…It follows, therefore, that 17 and 18 and 3 and 21 must have the configurations depicted in Scheme 2. 23 Differentiation of the two amino acid functionalities of 19 is possible. Thus, deprotection of N-Boc under mild acid conditions followed by treatment with triphosgene in the presence of triethylamine gave oxazolidinone 4 which can be engaged in the synthesis of the AB-COD ring of vancomycin.…”

“…Finally, comparison of the CD spectra of 19 and 20 with those of actinoidic acid derivatives reported in the literature allowed us to determine their axial chirality to be M and P , respectively (Scheme ). It follows, therefore, that 17 and 18 and 3 and 21 must have the configurations depicted in Scheme 3 …”

Strained-Cyclophane-Induced β-Turn Template: Design, Synthesis, and Spectroscopic Characterization

“…On the other hand, the CD spectra for compound 1a , the atropisomer of 2 , contained a minimum at ∼200 nm and a maximum at ∼220 nm, exactly the opposite of the expected spectrum of a type-II β-turn. Since it is known that atropisomers can display CD spectra opposite in sign, we hypothesized that this might be the case for the β-turn motifs. CD spectra similar to 1a were observed for compound 1b , indicating that this trend may be a general phenomenon.…”

Nonconventional Stereochemical Issues in the Design of the Synthesis of the Vancomycin Antibiotics: Challenges Imposed by Axial and Nonplanar Chiral Elements in the Heptapeptide Aglycons

“…For example, Jeffs et al has isolated amino acid components from the controlled hydrolysis of vancomycin and aridicin. [12] Both atropisomers of the biaryl-containing diamino diacid, referred to as actinoidinic acid, have been isolated in pure form and individually equilibrated at 100 8C to afford a 2:1 equilibrium ratio of atropisomers where the R (unnatural) isomer is favored (Scheme 2 a). This result can be contrasted with the equilibration of the M(5 ± 7) cyclic tripeptide 8(R) which now favors (dr 89:11) the natural atropisomer 8(S) (Scheme 2 b).…”